Trunked communication systems are known to comprise a plurality of communication units, a limited number of communication resources that are transceived via a predetermined number of repeaters, or base stations, and a communication resource allocator that allocates the limited number of communication resources among the plurality of communication units. The communication units may be portable radios and/or mobile radios. The communication resources may comprise a TDM (time-division multiplexed) bus, a carrier frequency, a pair of carrier frequencies, or any RF (radio frequency) transmission means.
In many systems, the communication resource allocator for each coverage area is a distributed infrastructure connected to each of the repeaters via a local area network. One repeater is designated as an active resource controller, also called an active master repeater or a master repeater, which allocates communications resources for all communication requests in the coverage area via the local area network, thereby providing control for the trunked communication system. Although typically only one repeater maintains this function for a coverage area, two or more, perhaps even all, repeaters in each coverage area are capable of performing as the master repeater, in case a repeater becomes inoperative or some other reason. When the active master repeater becomes inoperative, the remaining repeaters choose a new active master repeater, and communications continue.
If the local area network develops a break, thus separating the master repeater from any number of repeaters, the separated repeaters choose a new master repeater, thus two active master repeaters and hence two systems exist for the same coverage area for the same group of users. Two or more such systems can cause turmoil in resource allocation, such as both master repeaters allocating the same frequency or time slot to different users at the same time, or allocating different resources to the same user for one call. Other difficulties arise when a group call must be established, as some units from a group may be assigned to one system, and other units from the same group may be assigned to the other system, resulting in group members missing group calls. Many other undesirable communication trouble may result when a single system splits into two separate systems. Clearly, this situation must be avoided.
Accordingly, there is a need for a method of reestablishing singular control of the available resources in a communication system at all times.